It appears after some testing with my current code base and online examples, that groupHeaderTemplate's are not compiled against the angular scope like the rowTemplate's. I'm not sure if these examples save or not, but you can see an example here:
http://dojo.telerik.com/EduV
Note clicking the row template checkbox hits the console message, whereas the groupHeaderTemplate does not. Is this a known issue?
http://dojo.telerik.com/EduV
Note clicking the row template checkbox hits the console message, whereas the groupHeaderTemplate does not. Is this a known issue?